(AOL Autos) -- You may already have seen an ominous looking radar and camera perched atop a traffic light in your neighborhood. And almost all drivers have seen a patrol car cruising a freeway looking for speeders, or a law-enforcement officer standing at the side of a road wielding a radar gun.

But most have yet to see a freeway speed camera, which are common in Europe but currently are operated in just two U.S. states.

Opponents and backers of speed cameras both suggest that eventually speed cameras will become the norm on U.S. freeways. But just how likely is a nationwide roll-out? And what factors stand in the way? We take a look.

Sponsoring legislation in Maryland

Maryland Gov. Martin O'Malley signed into law on May 19 Senate Bill 277, allowing the use of speed cameras in highway work zones and within a half-mile radius of schools, which means that they can be placed on freeways under these conditions.

Maryland is only the second state behind Arizona to codify the use of freeway speed cameras into law. Hawaii piloted a program but dropped it, and similar programs near San Jose, California, and in southern Florida were dismantled after they were found to be operating outside of state law. Maryland's law takes effect on October 1.

"Maryland is in a unique position," said Sean Adamec, the governor's spokesman said.

Don't Miss

"A pilot program in Montgomery shows it worked; it lowered incidences of fatalities, crashing and speeding and made neighborhoods safer. It's safer for kids, road workers and it's been shown to work based on evidence. The point of them isn't to raise money but to catch speeders and that in turn makes neighborhoods safer. AOL Autos: Learn how Police catch you speeding

"We wouldn't propose any tax on motorists traveling at safe speeds. If it was revenue rising we would've done it years ago, [but cameras] slow people down so they don't need to levy so many fines. Of course there is a financial impact to make roads safer with less fatalities, but in the end you can't put a price on the life of a child," said Adamec.

Fighting legislation in Arizona

Sam Crump, an Arizona assemblyman who is opposed to the speed cameras and has backed legislation to have them removed from the state's freeways in 2010, says the main backing for speed cameras within Arizona has come from "senior citizens groups," but there has been a surprising agreement between his core conservative followers and college students over privacy concerns.

"It's been the subject of some debate since we introduced it and some legislators have been surprised by the controversy," Crump said. "We expect it to come up for a vote in the next couple weeks. If it fails, we'll say more power to the people. But every time [a freeway speed-camera initiative] has been up for a vote in any place it has failed."

Arizona's former governor, Janet Napolitano, predicted Arizona's freeway camera system would generate $90 million in profit for the state in 2009, and $34 million for the private company that runs it. Crump, however says the system's total profit has been in the range of "$20 to $25 million a year," which leads him to suggest that speed camera detractors who say it's only a device to make money could be wrong.

"I caution people that it really is technology in the hands of Big Brother," Crump said. "We've got 70 or so [freeway speed cameras] right now, and they're looking at [a total of] 200."

Safety at issue

Russ Rader, at the Insurance Institute of Highway Safety, says that, outside of freeways, speed cameras are used in 48 communities nationwide, including in Arizona, Colorado, Illinois, Iowa, Louisiana, Maryland, Massachusetts, New Mexico, Ohio, Oregon, Tennessee, Washington, and Washington DC. The group's research shows that photo enforcement "works to slow drivers down. Cameras do what police officers can't -- enforce speed limit laws 24/7. Speeding is a major safety problem on our roads. It contributes to one-third of all crash deaths." AOL Autos: Caught at 100 mph: Now what?

The IIHS found that speed cameras "can substantially reduce speeding on a wide range of roadway types. Six months after implementation of speed cameras on residential streets and school zones in Montgomery County, Maryland, in 2007, the proportion of drivers exceeding speed limits by more than 10 mph declined by about 70 percent. Implementation of a 9-month pilot program using fixed speed cameras on a busy urban freeway in Scottsdale, Arizona, in 2006 was associated with up to a 95 percent decrease in the odds that drivers would travel more than 10 mph above the posted 65 mph speed limit."

"The main argument opponents use against camera enforcement is that it can be a cash cow for local governments," Rader said.

"If you don't like the idea of sending revenue to your local government, don't break the law. It's hardly unreasonable to expect drivers to stay within 10 mph of the speed limit. I have an elementary school in my neighborhood, which is bisected by a major commuter road where drivers regularly speed like banshees. I want those drivers ticketed. Period. There aren't enough police officers to do that everywhere."

Nationwide rollout?

Newspaper.com's Richard Diamond, an opponent of speed cameras, says it's hard at times to weigh which "side" -- opponents of the cameras, or their detractors -- is "winning."

"There are places where cameras are advancing, and places where they're retreating," said Diamond. "For politicians, the desire is on increase, but whether they can get away with it, that level has gone down."

He says lawmakers in Wisconsin, Ohio, Montana and Mississippi failed to get a freeway speed camera measure onto a ballot, but points to Maryland as an example of lawmakers' success. He says 13 states have specific laws banning freeway cameras, but he sees a natural progression from states using red-light cameras to using freeway speed cameras.

"The biggest issue opponents have is it creates a legal system where you're presumed guilty without a trial," Diamond said. "If a database says you're a criminal, you are. Once you let in the cameras it opens the door that this is OK."

He says protesting freeway speed cameras can be an arduous task.

"Somebody willing to go to the effort for 30 days and grab 20,000 signatures takes dedication."

Grassroots activism

Todd Kandaris, at Camerafraud.com says his Arizona-based group's campaign against freeway cameras started late in 2008 and his group's member numbers have swelled from 100 to about 1500. He says the group works to bring attention to the issue through protests and publicity stunts.

"Early on we concentrated on raising awareness and getting attention, [with] groups of people getting out there and protesting," said Kandaris. "We find that highway overpasses work well. Thousands [of motorists] go by in a given hour, and [it gets] lots of media attention. We demo'd in front of the manufacturer's headquarters. Earlier this year we introduced a citizen's initiative with the secretary of state, attempting to put the issue on the ballot, to let citizens vote on it in 2010."

He says the group must collect more than 150,000 signatures by July 2010 to place the issue on the statewide ballot, and is working with groups in Virginia, Louisiana, D.C., Texas and Ohio. "Cameras have never withstood a vote of the public, which tells you this is a device used by politicians and corporations to make money. It's not like we're a bunch of evil speeding people, we want traffic control as much as everyone else. We just think this is just a device to bilk money out of the public."

Legal standpoint

Sherman Ellison, a California lawyer who fights regular speeding and traffic tickets, says that a key legal issue is the data-gathering system by which driver information is collected by companies and then distributed to law-enforcement agencies, who then issue the citation to the car's driver, or owner (which varies by state). AOL Autos: Learn what cops are thinking when they pull you over

"If you were driving down the street and ran a red light and an officer pulled you over he'd write a ticket for failing to stop," Ellison said. "He would have visually observed [the offense] and you'd either plead or go to trial, where you'd be able to ask him for proof of that. In the photo context there is no officer, it's just a camera connected to a laptop, and that system sends that information to a company, whether that's Redflex or another, that sends data digitally to the contractor. AOL Autos: What to do when you get pulled over

"The difficulty in this process is they will crop or enhance these photos or whatever they feel they have to do, for the determination of whether they broke the law. I demand that they prove this is a true and correct photograph and rarely they'll go through that process."

Redflex responds

Cristine Weeks, a spokeswoman for Redflex, an Australian company headquartered near Phoenix that works in tandem with seven other vendors enforcing speed limits nationwide and operates Arizona's freeway speed-camera system, says several studies -- including those of the IIHS, Arizona State University and the Arizona Department of Transportation -- have demonstrated camera "efficacy and accident reductions."

She says the Redflex infrastructure was set up without any additional taxpayer funds and that the company contracts with various state and city departments in the same way as a waste-management company would. The company reported $88.2 million in revenue for its global operations in 2008 -- and an annual increase of 43 percent in U.S. traffic revenues from $44.3 million to $63.3 million -- and an operating profit of $10.6 million.

She says the company's data-gathering process involves analyzing digital still images as well as streaming video, and that the company performs a quality check of any images before sending them to law-enforcement officers, who review all of the evidence before authorizing any citation.

"Nothing is changed on the image. They are not 'Photoshopped,'" Weeks said. "It is impossible to 'shop in a light system. In the early days it was a question many wanted to know. [But] the agencies are walked through to see how the process works, and a violator can view their own video."

She says radars similar to mobile-police devices measure a motorist's time over distance and any breach of the speed limit results in a camera image of the front of the car --including the driver, and the car's rear license plate. She says although Arizona freeway drivers are not levied points on their license for any breach of the law, that as drivers are forced to pay more fines, they become "more aware" of their driving patterns, and modify their driving accordingly. AOL Auto: 10 ways to avoid a speeding ticket

When asked if she thinks a nationwide system of freeway speed cameras is likely, Weeks offers a cryptic response: "I think, you know, take a look at western Europe, which is 10 to 15 years ahead of U.S. applications."